Tait TM8100 mobiles Service Manual page 378

Task 24 —
Power Control
and Shaping Filter
378 Transmitter Fault Finding (25W)
In this task any faults in the power-control and shaping-filter circuitry will
be located:
1. Measure the voltage at pin 8 of IC303 (see
power-control circuit. The voltage should be:
pin 8 of IC303: 7.4 ± 0.5V
2. If the voltage is correct, go to
command 32 and return to
3. Measure the voltage at pin 10 of IC303 (see
power-control circuit. The voltage should be:
pin 10 of IC303: 4.8 ± 0.5V
4. If the voltage is correct, go to
Enter the CCTM command 32 to place the radio in receive mode.
5.
6. Check C322, C324, R342, R347 (see
control circuit.
7. Repair any fault revealed by the checks in
(see Figure 12.8) if none of the other components is faulty. Confirm
the removal of the fault and go to
repair failed, replace the board and go to
8. Measure the voltage at pin 1 of IC301 (see
shaping-filter circuit. The voltage should be:
pin 1 of IC301: 4.8 ± 0.5V
Enter the CCTM command 32 to place the radio in receive mode.
9.
10. If the voltage measured in
go to Step 12.
11. Check the components R334 (see
(see Figure 12.12) and go to
12. Check the components between the
IC301 (see Figure
13. Repair any fault revealed by the checks in
Replace IC301 (see
is faulty. Confirm the removal of the fault and go to
page 163. If the repair failed, replace the board and go to
Tasks" on page
Step 3. If it is not, enter the CCTM
Task 23.
Step 5. If it is not, go to
"Final Tasks" on page
Step 8 is correct, go to
Figure
Step 13.
PWR
12.8) and go to Step
Figure 12.8) if none of the other components
163.
© Tait Electronics Limited November 2007
Figure 12.8) in the
Figure 12.8) in the
Step 8.
Figure 12.8) in the power-
Step 5. Replace IC303
163. If the
"Final Tasks" on page
Figure 12.8) in the
Step 11. If it is not,
12.8) and C319
test point and pin 1 of
13.
Step 11 and Step 12.
"Final Tasks" on
"Final
TM8100/TM8200 Service Manual
163.